"Cannot call 'ta.rsi' with argument 'length'='lowers'. An argument of 'series float' type was used but a 'simple int' is expected"

I'm getting this error in pine script could someone help me to solve this code please Here is my code

Cannot call 'ta.rsi' with argument 'length'='lowers'. An argument of 'series float' type was used but a 'simple int' is expected

source =(high + low + close)/3
length = input.int(14, minval=1) 
Highlight=input.bool(true, title="Highlight Oversold and Overbought")
uppers = math.sum(volume * (ta.change(source) <= 0 ? 0 : source), length)
lowers = math.sum(volume * (ta.change(source) >= 0 ? 0 : source), length)
mfi = ta.rsi(uppers, lowers)
mfp = plot(mfi, color=color.gray, linewidth=1)